w9 Flashcards
What is FES?
Functional electrical stimulation
a means of producing useful movement in paralysed muscles. Electrical impulses are applied using either skin surface or implanted electrodes and cause muscles to contract in a controlled manner
health conditions that limit hand function
paralysis
paresthesia (tingling or numbness)
hypertonicity (muscle tightness or spastic)
gross trauma (affects sheer movement)
scar tissue
muscle shortening and lack of supplemeness
Describe the spinal cord injury model
mostly 17-19 years old males who are young and well. Life expectancy is that of non injured person.
single assult and not associated with degenerative disease
often severe disability/injury
cognitively intact and able to make a substantial contribution to society if enabled
C5/6 for hand function as workspace good
which spinal cord areas are more vulnerable to injury and why
neck region (C region). most common region of injury.
C7 sticks out along the back? => Makes it more vulnerable to trauma
what are the symptoms of a complete c6 injury
no sensation or motor function below c6 region
have some remaining function in deltoid muscles, biceps, and wrist extensors
Should be able to bend wrists back (in turn, manipulates finger movement)
what are the symptoms of a complete c5 injury
no sensation or motor function below c5 region
have some remaining function in deltoid muscles and biceps.
Person can raise his or her arms and bend elbows.
what do tetraplegics need to have to qualify them for functional electrical stimulation of hand movement
ability to move their arm in 3D space
can do tenodesis grasp
what are the principles of functional electrical stimulation
Below the spinal cord injury, the spinal cord / motor neurons are still intact. can still measure afferent signals (PNS -> CNS). These signals will be hypertonic (overly large) because there is no inhibition coming from the brain.
nerves from the injury site do not work -> lower motor neuron injury
can stimulate peripheral nerves or muscles directly using stimulation units
what are epimysial, intramuscular, and percutaneous electrodes
epimysial: flat electrode sits on top of muscle. stimulates nerves?
intramuscular: rod/stub shape that goes into muscle. stimulates muscle directly.
percutaneous: small helical, needle-like electrode. type of intramuscular electrode. has skin interface (comes out through skin).
what are the limitations of stimulating muscles directly
need a lot of current
risk of degrading electrode from electrolysis
what are the components of a fully implantable FES system
control unit with RF transmitters. control system e.g. joystick, control system on opposite shoulder.
implantable receiver / stimulator
electrode leads with in-line connectors
electrodes
what are the two types of hand movements that can be restored using FES systems
lateral or key grasp: grasp small objects, precision grip. thumb is pressed against other fingers e.g. holding spoon, pinching.
palmer grasp: for large and heavy objects. thumb is extended and opposite of other fingers e.g. holding glass of water
what are the traditional methods of treating upper limb injuries
these may be used if there is no wrist extension capability
tendon transfers
rotational osteotomy - bones are cut and twisted to provide better functional position
botulinum toxin & phenol injections - knocks out peripheral nerves
surgical releases - free up joints
physiotherapy / occupational therapy
nerve transfers
what are the principles of nerve transfer
people with spinal cord injuries have redundant but healthy nerves
they may donate these nerves to people who would gain substantial functional benefit
what functions can be restored using nerve transfer
elbow extension
hand opening: subset wrist, finger, thumb, extensors and thumb abductor
grasp: finger and thumb flexors and forearm pronator
